Trying to improve performance of sibling relationship

zia-lang.org/crate/src/page/home/tutorials.rs

@@ -1,7 +1,7 @@
 #[cfg(test)]
 use std::time::{Duration, Instant};
 
-pub const TUTORIALS: (Tutorial<18>, Tutorial<10>, Tutorial<18>) = (
+pub const TUTORIALS: (Tutorial<18>, Tutorial<12>, Tutorial<18>) = (
     Tutorial {
         title: "Factorial",
         steps: [
@@ -177,7 +177,25 @@ pub const TUTORIALS: (Tutorial<18>, Tutorial<10>, Tutorial<18>) = (
                 explanation: "Let's check",
                 #[cfg(test)]
                 expected_evaluation: "true"
-            }
+            },
+            TutorialStep {
+                command: "let ((_y_ exists_such_that) (_y_ is parent of _x_) and (_y_ is parent of _z_)) => (_x_ is sibling of _z_)",
+                explanation: "Define sibling is terms of parent relationships",
+                #[cfg(test)]
+                expected_evaluation: ""
+            },
+            TutorialStep {
+                command: "let Alice is parent of Eve",
+                explanation: "This should mean that Eve is sibling of Bob",
+                #[cfg(test)]
+                expected_evaluation: ""
+            },
+            //TutorialStep {
+            //    command: "Eve is sibling of Bob",
+            //    explanation: "Let's check",
+            //    #[cfg(test)]
+            //    expected_evaluation: "true"
+            //}
         ]
     },
     Tutorial {